This is going to be a picture overload, for Mike's benefit.
On the top floor there is a mirror maze and a historic carousel. The ride used to reside in Broadripple Park, near where my dad grew up, and he remembers fighting to get on the tiger. After many years, it began to suffer damage from exposure, and it was put in storage after a collapse. Several years later, it was restored and placed in the Children's Museum, and I, too, remember riding it my whole life. It gives our family a thrill to ride it now with my little ones. Members ride for free, non-members have to buy tokens for about $1 a piece.
Outside the carousel is a large play area complete with a tree house and an ice cream shop.
"Sorry, we're out of chocolate ice cream and root beer."
On the other side of the top floor is the ScienceWorks. Here there is a hands-on watershed area for kids to experience how a river flows and changes, a mini construction site, and several areas dedicated to Indiana wildlife.
Between the two they had an area set up with stacking types games. The boys played Jenga and got to nearly 40 levels (with a little help from their engineer mom). The staff lady said we broke the record.
One level down is a Playscape for preschoolers. It has a water-flow table, sandbox, and a play farm and construction site. One of my favorite features is the infant playground- a large padded area with a knee-high wall and lots of things for them to explore- balls of varying shape, size, and texture, light switches, buttons, drawers, doors that open or slide, and blocks. Next to it is a padded mini obstacle course for your little crawler. They also have story readings every 30 min or so. Age is strictly limited to kids under 5- not even older siblings are allowed in, and strollers must be parked just inside the door. On crowded days the area is often full to the point that they turn people away.
On the bottom floor/basement is the planetarium and the Lilly Theater. A winding "What if..?" exhibit begins with ocean exploration, which leads into an (old) dinosaur area, which leads into an Egyptian exhibit with a real mummy. Nicholas also gets his train fix down here with the Reuben Wells, a steam engine pusher with a toolcar. This was another one of my favorites as a kid. A train platform and station next to it holds a collection of antique toy trains, the mandatory Thomas playset, and a couple train models, one which shows how the Reuben Wells used to do its work. Every half-hour the train has a light and sound event to make it seem as if the train is steaming away. The kids get a huge thrill out of it. Or maybe it's just me.
If you end up visiting, what you can't miss upon arriving is the Dinosphere. And when I say you can't miss it, I mean you can't fail to notice several dinosaurs made to look like they are crashing out of the side of the building as you drive up the street. Great photo op for the family. Inside the Dinosphere itself, you could spend an entire day. The coolest feature in my opinion is the dinosaur dig, where kids can pretend they are doing the real thing. What makes it so cool? The "dirt" is actually pretty solid, and they recover it every few months, so it's not just a big sandbox- it's dynamic and kids get a better sense of how difficult it really is to recover dinosaur bones.
And that's really only about 2/3 of what they have there- not to mention the huge expansion under construction and a large area they creating a new permanent display in. See? Told you I was spoiled.